Ulrike I. Attenberger MD, Presenter: Nothing to Disclose

Val Murray Runge MD, Abstract Co-Author: Research grant, Bracco Group Research grant, Bayer AG

James Earl Dix MD, Abstract Co-Author: Nothing to Disclose

Michael Joseph Marra ARRT, Abstract Co-Author: Nothing to Disclose

Henrik Jakob Michaely MD, Abstract Co-Author: Consultant, Bayer AG

To demonstrate the improved sensitivity at 3 T of a new 3D T1-weighted, fast spin echo based sequence (SPACE) for the detection of brain metastases in comparison to a conventional 3D magnetization prepared rapid gradient echo sequence (MP-RAGE).

28 patients with brain metastases were included in this IRB approved study, performed at a facility for stereotactic radiation therapy planning. All patients underwent post-contrast imaging with both 3D T1-w MP-RAGE and 3D T1-w SPACE (voxel size 1.1x1x1 mm3, scan time 4:46 vs 6:14 min:sec) using a 12 channel coil. Two external readers independently read the scan sequences in a blinded fashion. The result was then compared to an on site read, performed by a third reader, with access to all clinical information and all scans (pre- and post-contrast), including sagittal and coronal thin section reformats. SNR was compared in 5 volunteers using both 12- and 32-channel head coils.

285 brain metastases were detected overall, on the basis of the defined gold standard. On the MP-RAGE sequence, reader 1 detected 55.4% and reader 2 detected 52.6% of these lesions. On the SPACE sequence, both readers detected a substantially higher number of metastases (82.5% and 88.8%), with a statistically significant difference in comparison to the number of lesions counted on the MP-RAGE scans (reader 1 p=0.006, reader 2 p=0.003). There was also a markedly improved correlation for the SPACE (reader 1 r=0.904 and reader 2 r=0.916) vs the MP-RAGE (reader 1 r=0.614 and reader 2 r=0.558) scans. The lesions missed on MP-RAGE were all 5 mm or less in diameter. SNR was higher for SPACE than MR-RAGE using the 12-channel coil (8.9±1.2 vs 6.7±0.7, p=0.009), but not using the 32-channel coil, where scan time was optimized and standardized to 3.5 min for each sequence. Vascular enhancement was absent on the SPACE sequence, and gray-white matter contrast less (2.2±1.3 vs 4.2±1.2, p=0.03).

This study demonstrates the markedly improved sensitivity of a new, work-in-progress, 3D T1-w fast spin echo sequence (SPACE) in comparison to a 3D T1w gradient echo based scan (MP-RAGE scan) for the detection of brain metastases at 3 T.

3D T1-weighted SPACE has markedly improved sensitivity for brain metastases, due to its spin echo base and other characteristics facilitating lesion recognition, and is recommended for 3 T.  

Attenberger, U, Runge, V, Dix, J, Marra, M, Michaely, H, Improved Detection of Brain Metastases at 3 T, Using a Work-in-Progress 3D Spin Echo-based T1-weighted Sequence, SPACE, in Comparison to a Current Accepted Standard, 3D MP-RAGE.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8007237.html